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Oklahoma State discusses extra-label drug usage in livestock

By Randy Pirtle

E-E Columnist

Animals, like humans, are susceptible to bacterial and parasitic infections and frequently require medications or drugs to treat these various conditions.

Veterinarians and producers are fortunate in that we have several antimicrobial drugs available to treat various infections in food producing animals. These antimicrobial medications have labels approved by the Food and Drug Administration. The product label includes important information such as indications, directions, route of administration, precautions and withdrawal period. Deviations from following the label directions could result in altered effectiveness, potential toxicity to the animal and violative meat or milk residues.

The FDA recognizes that certain conditions may arise in which a drug will need to be used in an extra-label manner (extra-label drug use) and recognizes the professional judgment of veterinarians in making those recommendations. Any ELDU of an FDA approved drug is by definition a prescription drug and requires the involvement of a licensed veterinarian. In order for ELDU to occur, a valid veterinarian-client-patient-relationship must exist.

Briefly, according to Dr. D.L. Step, OSU veterinarian, the following must be met regarding a valid V-C-P-R and for a food animal veterinarian to prescribe the extra-label use of a medication:

1) There is no approved new animal drug labeled for a particular condition or the new animal drug is clinically ineffective.

2) The licensed veterinarian has assumed the responsibility for making medical judgments regarding the health of the animal(s) and the need for medical treatment.

3) The licensed veterinarian has sufficient knowledge of the animal(s) to initiate at least a general or preliminary diagnosis of the medical condition.

4) The licensed veterinarian is available for follow up in case of adverse reactions or failure of the regimen of therapy.

5) The licensed veterinarian establishes an extended withdrawal period based on appropriate scientific evidence prior to marketing the animal or product (such as milk, eggs).

6) The treated animal(s) must be properly identified and the identity is carefully maintained. Records of ELDU must be maintained by the veterinarian for a minimum of 2 years.

7) The owner of the animal(s) agrees to follow the veterinarian’s instructions.

ELDU is limited to circumstances when suffering or death may result from failure to treat or when the health of the animal is threatened. ELDU is not permitted for production (growth, reproduction) enhancement, for reducing the treatment costs. While a veterinarian can legally prescribe many products for ELDU, there are some that are explicitly illegal for extra-label use. Many of these products are not labeled for any use in food animals and should never be used for any reason. For others, the prohibition of ELDU means those products can only be used for the specific condition for which it is labeled and should not be used for any other reason. Extra label use of feed medications is prohibited by FDA. The law requires that no violative drug residue may result from the ELDU.

It’s that time of year again. Leaves are rapidly falling from deciduous trees so it’s a good time to stop and think about options for handling the litter. Although a scattering of leaves won’t harm the lawn, excessive cover prevents sunlight from reaching turfgrass plants. Turf left in this state for an extended period will be unable to make the carbohydrates needed to carry it through the winter.

There are options for dealing with the fallen leaves other than bagging them up and putting them out for the trash collector. Composting is a great way to handle the refuse. Compost can then be used in the vegetable garden and flowerbeds. If you do not compost, you can mow leaves with a mulching mower and let shredded leaves filter into the turf canopy. (A side-discharge mower also will work, but it won’t shred the leaves as thoroughly.) This method will be most effective if you do it often enough that leaf litter doesn’t become too thick. Mow while you can still see grass peeking through the leaves.

You may wonder whether this practice will be detrimental to the lawn in the long run. Research at Michigan State University in which they used a mulching mower to shred up to about one pound of leaves per square yard of lawn (one pound is equal to approximately 6 inches of leaves piled on the grass) for five consecutive years, found no long-term effects of the shredded leaves on turf quality, thatch thickness, organic content of the thatch or soil test results (pH, nutrients, etc.). Granted the environment is much warmer in Oklahoma but no known disease associations have been documented.

However, if you mow leaves and have a cool-season lawn, it makes sense to be on a fall nitrogen fertilization program which you should be doing anyway. If you have a warm-season lawn such as Bermuda you can still use this technique but wait to fertilize until next late May or early June.